CNRFC - Hydrology - Observed River/Reservoir Conditions

MERCED RIVER - YOSEMITE NP AT HAPPY ISLES (HPIC1)

Latitude: 37.73º N	Longitude: 119.56º W	Elevation: 4017 Feet
Location: Mariposa County in California		River Group: San Joaquin

Monitor Stage: N/A

Flood Stage: 7.5 Feet

Observed Data Credit
	Raw streamflow data is provided by the US Geological Survey (USGS). View USGS Data for this station location.

Historical Stage/Flow Data
Note: Water Year 2025 is currently showing peak daily mean values. These will be updated to instantaneous peaks in the coming months.
Water Year	Peak Discharge (cfs)	Stage (feet)	Date
Most Recent 5 Years
2025	2,100	5.89	May 11, 2025
2024	2,980	6.80	May 19, 2024
2023	4,980	8.42	May 23, 2023
2022	2,430	6.25	Oct 25, 2021
2021	1,410	5.02	May 7, 2021
Historical High Stage/Flow Events (Period of Record - Aug 1915 to Present) - Ranked by Flow
1997	10,100	13.27	Jan 2, 1997
1956	9,840	12.73	Dec 23, 1955
1951	9,260	11.55	Nov 18, 1950
1965	9,240	11.50	Dec 23, 1964
1938	8,400	10.40	Dec 11, 1937
2018	8,060	10.09	Dec 07, 2018

Location Photographs
Upstream Photo	Gage House Photo	Downstream Photo

ESRI™ Locator Map

Official 7 Day National Weather Service Forecast (CAZ324)

Today: Partly sunny. Chance of rain late in the morning. Chance of rain showers and slight chance of thunderstorms in the afternoon. Highs 50 to 58. East winds up to 5 mph shifting to the west in the afternoon. Chance of precipitation 40 percent.

Tonight: Partly cloudy with a 20 percent chance of rain in the evening, then clear after midnight. Lows 36 to 46. Northeast winds up to 10 mph.

Saturday: Sunny. Highs 55 to 61. East winds up to 5 mph shifting to the west in the afternoon.

Saturday Night: Mostly clear. Lows 38 to 46. Northeast winds up to 5 mph.

Sunday: Mostly sunny. Highs 56 to 62. East winds up to 5 mph shifting to the west in the afternoon.

Sunday Night: Partly cloudy in the evening then becoming mostly cloudy. Lows 37 to 45.

Monday: Mostly cloudy. Chance of rain in the afternoon. Highs 50 to 56. Chance of rain 40 percent.

Monday Night: Mostly cloudy. Chance of rain in the evening, then chance of rain showers after midnight. Lows 32 to 40. Chance of precipitation 50 percent.

Tuesday: Rain showers and snow showers likely. Light snow accumulations. Highs 40 to 46. Chance of precipitation 70 percent.

Tuesday Night: Colder. Mostly cloudy. Rain and snow likely in the evening, then chance of snow and rain after midnight. Moderate snow accumulations. Lows 26 to 34. Chance of precipitation 70 percent.

Wednesday: Partly sunny with a 40 percent chance of snow and rain. Highs 42 to 48.

Wednesday Night: Mostly cloudy with chance of rain and snow in the evening, then partly cloudy after midnight. Lows 27 to 35. Chance of precipitation 30 percent.

Thursday: Mostly sunny. Highs 47 to 53.

Flood Impacts
13.27 Feet	Flood of Record: 1/2/97. $178 million in damage to Yosemite Valley.
10.0 Feet	Northside Drive at Wosky Pond, Southside Drive at Chapel Meadow, El Capitan crossover, and Sentinel crossover are impassable to vehicles.
8.2 Feet	Swinging Bridge overtops. Water on road at Northside Drive, Southsie Drive, El Capitan crossover, and Sentinel crossover.
7.5 Feet	Flood Stage. Housekeeping camp and Yosemite Valley backpacker campground begin to flood.
7.0 Feet	North Pines and Lower Pines campgrounds begin flooding.

Product Disclaimer

This river graphic is not intended to serve as a substitute for official flood watches, warnings, advisories, or statements issued by the NWS San Joaquin Valley-Hanford Weather Forecast Office. Observations are preliminary and subject to change. River levels identified as "forecast" should be consistent with those contained in official NWS products. River levels identified as "guidance" have significant uncertainty due to future weather or reservoir regulation and are provided for planning purposes only.

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